Materials Processing Fundamentals: Process Studies and Optimizations
Sponsored by: TMS Extraction and Processing Division, TMS Materials Processing and Manufacturing Division, TMS: Process Technology and Modeling Committee
Program Organizers: Samuel Wagstaff, Oculatus Consulting; Alexandra Anderson, Gopher Resource; Jonghyun Lee, Iowa State University; Adrian Sabau, Oak Ridge National Laboratory; Fiseha Tesfaye, Metso Outotec Finland Oy

Wednesday 8:30 AM
March 2, 2022
Room: 213D
Location: Anaheim Convention Center

8:30 AM Introductory Comments

8:35 AM  
Thermoelectric Magnetohydrodynamic Control of Melt Pool Dynamics and Microstructure Evolution in Direct Energy Deposition Additive Manufacturing: Xianqiang Fan1; Tristan Fleming2; David Rees1; Yuze Huang1; Yunhui Chen1; Sebastian Marussi1; Robert Atwood3; Andrew Kao4; Peter Lee1; 1University College London; 2Queen’s University; 3Diamond Light Source Ltd; 4University of Greenwich
    Large thermal gradients in the melt pool during additive manufacturing (AM) generate large thermoelectric currents. The application of an external magnetic field introduces a Lorentz force which drives fluid flow in the melt pool, known as thermoelectric magnetohydrodynamics (TEMHD). However, the relative magnitude of TEMHD flow to Marangoni and buoyancy flow is poorly understood. To investigate this, a system to apply a magnetic field with a variable-orientation was developed and mounted into a DED-AM process replicator. A magnetic field of 230 mT is shown to increase the melt pool depth when applied parallel to scan direction. Further, when the polarity of the magnetic field was reversed normal to the scan direction, alternating thin and thick layers were produced. This is shown to be caused by the influence of magnetic field orientation on TEMHD flow by comparison to computational modelling of the flow and microstructure development, revealing the underlying hydrodynamic mechanisms.

8:55 AM  Cancelled
Significance of Post-processing Subtransus Heat Treatment on the Microstructure and Mechanical Behavior of Additively Manufactured Ti-6Al-4V Alloy: Abbas Mohammadi1; Bonnie Whitney1; Akshatha Chandrashekar Dixith1; Anthony Spangenberger1; Cory Cunningham2; Jared Gross2; Austin Mann3; Diana Lados1; 1Worcester Polytechnic Institute; 2Boeing Additive Manufacturing; 3Boeing Research & Technology
    Laser powder bed fusion (LPBF) additive manufacturing has drawn significant attention in recent years due to the outstanding capability to readily fabricate complex parts with excellent performance. However, the inhomogeneous microstructures with partially textured structures and high residual stress strongly affect mechanical properties and isotropic behavior of LPBF materials. To gain insight into the achievement of desired mechanical properties in LPBF Ti-6Al-4V, single- and double-step subtransus heat treatments were investigated. Post-LPBF heat treatments were performed in vacuum and air furnaces from 650 to 950 °C (using different cooling rates) to relieve residual stress and produce mixed (α’ + α + β) or lamellar (α + β) microstructures that will provide superior combinations of strength and ductility. Microstructures and mechanical properties were examined using optical, scanning electron, and transmission electron microscopy, electron backscatter diffraction (EBSD), as well as tensile testing and Vickers microhardness measurements.

9:15 AM  Cancelled
Development of Activated Carbon from Coconut Shell as AN Absorbent in a Refrigeration Thermodynamic Cycle: Ademola Agbeleye1; Manasseh Oyekeye1; 1University of Lagos
    Activated carbon has found its use in arresting or controlling pollutants due to its extensively developed porous structure and large surface area. This study developed activated carbon from coconut shells, an agricultural waste product to be used as solid adsorbent in a refrigeration thermodynamic cycle with methanol as adsorbate. The coconut shell was carbonized by burning in a kiln and chemically activated with phosphoric acid. Further work involved the evaluation of its properties such as the iodine number (906.67mgg–¹), Ash content (1.2%), bulk/apparent density (0.578 g/ml), Tamped density (0.554 g/ml), Hardness value and particle size distribution. From the results obtained the manufactured sample was found to be suitable as an adsorbent for the proposed adsorbate.

9:35 AM  
NOW ON-DEMAND ONLY – Strategies for the Upgrade of a TBZC Product (Tetra Basic Zinc Chloride) by Selective Removal of the Impurity Chlorine: Lukas Hoeber1; Thomas Hofbauer2; Rana Ahmed3; Stefan Steinlechner1; 1CDL for Selective Recovery of Minor Metals Using Innovative Process Concepts; 2Andritz Metals; 3Montanuniversität Leoben
    When recycling materials containing zinc in hydrochloric acid processes, the precipitation of zinc can lead to the formation of various compounds which can be assigned to the group of zinc hydroxide chlorides. This research project aims to compare different approaches for the selective removal of chlorine as an impurity to obtain a cleaned zinc product from these materials. The removal of chlorine via soda leaching at atmospheric conditions as well as under overpressure in an autoclave was investigated. Furthermore, concepts were considered in which the chlorine can be evaporated and thus separated via selective temperature and atmospheric control. Thereby, a focus is on the simulation of pyrohydrolysis and clinkering for the separation of chlorine in gaseous compounds whereby zinc remains and can be brought to further processing. The simulations with multivariant parameters are carried out using the thermochemical calculation software packages FactSage and HSC Chemistry.

9:55 AM Break

10:15 AM  
Pulsed Electric Current Joining of Oxide-dispersion-strengthened Austenitic Steels: Fei Wang1; Xueliang Yan1; Xin Chen1; Nathan Snyder1; Michael Nastasi2; Khalid Hattar3; Bai Cui1; 1University of Nebraska-Lincoln; 2Texas A&M University; 3Sandia National Laboratories
    The solid-state joining of oxide-dispersion-strengthened (ODS) austenitic steels were realized using a pulsed electric current joining (PECJ) process. Microstructures of the austenitic grain structures and oxide dispersions in the joint areas were characterized using electron microscopy. Negligible grain growth was observed in austenitic grain structures, while slight coarsening of oxide dispersions occurred at a short holding time. The mechanisms of the PECJ process may involve three steps that occur simultaneously, including the sintering of mechanical alloying powders in the bonding layer, formation of oxide dispersions, and bonding of the mechanical alloying powders with the base alloy. The high hardness and irradiation resistance of ODS alloys were retained in the joint areas. This research revealed the fundamental mechanisms during the PECJ process, which is beneficial for its potential applications during the advanced manufacturing of ODS alloys.